Pulling the fender gives access to the door hinge bolts on the pillar. Removing the door this way makes it easier to put on and off, IMO. I am replacing rockers, cab corners, cab supports and both pillars right now. Usually there is more than just rocker rust.

Nope you can get them off with the doors on. You will need an air chisel to get the front spot welds that are in behind the fender. It will come off in bits and pieces. You will not however be able to fully spot weld it with the fender still on. If its clean and solid you could use adhesive to attach the new ones. If you are looking to fully clean and repair everything in behind you will need to take it all apart. If you are looking at a quick or temporary fix then it can be done with fenders on.

Thanks for all the help here, believe only the rocker is rusted but I'll know for sure once everything has been removed, probably tomorrow. No signs of any rust on inside of cab floor or kick panel. I'll take pictures as I progress.

Now have the patch panels but haven't been able to prepare rusted areas yet, trip to dermatology for some Liquid Nitro put me out of service, should have taken truck for a shot of the stuff.
C:\Users\Ron\Pictures\2016-04-29 (3)

Panels came but unable to prepare areas due to visit to Dermatology, hit with the liquid nitro and out of service few days (sun anyway). Should have taken truck in for some deep freezing for its cancer.

Just wanted to update and show my truck is back together and on the road once more. After these pictures were taken, sanded and repainted truck with another coat, hood; sides and tailgate needed help. (OK now but still some buffing to do, needed to use truck for hauling).